This invention relates to optical waveguides and more particularly to optical waveguide power dividers or couplers.
A power divider is an essential component of any amplitude modulator constructed with optical waveguides which operates by interfering two-phase shifted guided waves. Light passing through the two waveguides is controlled in such a manner that light may be shifted from one waveguide to another. Heretofore a 3-dB power transfer between optical waveguides has been achieved by providing synchronism between two optical waveguides over a critical interaction length, whose magnitude depends upon the coupling between the waveguides.
In prior art devices there are severe tolerance restrictions on both the smoothness and on their mean dimensions, i.e. length of the coupled guides. Such prior art devices have been set forth in an article "Improved Tolerance in Optical Directional Couplers," by M. G. F. Wilson et al., Electronics Letters, Vol. 9, #19, Sept. 20, 1973, pp 453-454.
This invention has been set forth in a published article, "Optical Modal Evolution 3-dB Coupler" by W. K. Burns, A. F. Milton, A. B. Lee and E. J. West, Applied Optics, Vol. 15, No. 4, April 1976, pp 1053-1065, which is incorporated herein by reference.